1. Field of the Invention
The present invention relates to encoding and decoding of image data, and more particularly, to an apparatus and method for encoding and decoding image data through adaptive quantization according to the number of bits by determining a quantization coefficient proportional the number of bits per pixel.
2. Description of Related Art
An image acquired by a camera is displayed with an appropriate size, i.e., a number of pixels, through sampling. When the image is displayed, the number of bits required to represent a value of each pixel is determined, and to display the image with high quality, an increase of the number of representable values is required, thereby increasing the number of bits. In addition, accompanying the development of image devices, the number of bits has gradually increased. For example, although 8 bits are used in many fields, recently, 10 or 12 bits are being increasingly used in application fields where high quality images are required.
For conventional image compression, compression schemes for 8-bit images have been generally developed. For example, VC-1 (VC-1 Compressed Video Bitstream Format and Decoding Process) corresponding to a compression video codec standardized by the Society of Motion Picture and Television Engineers (SMPTE) provides effective quantization schemes suitable for every case using various kinds of image information. However, in the quantization schemes used in VC-1, the number of bits per pixel is fixed at 8. Although an 8-bit image is popularly used for image coding schemes, a limitation in the image quality exists when the 8-bit image is used. Thus, considering the gradual increase of the demands for images having high quality, it is necessary to provide a method using a quantization scheme suitable even for an image using a number of bits per pixel greater than 8.